1. Field of the Invention
The present invention relates to a device for stacking flat articles to form one or more stacks into a box-shaped container.
2. Background Information
At the present time there are known several kinds of stackers designed to stack various flat articles, such as books, cassettes, records and the like, coming from a standard transport system or a sorting machine, into box-shaped containers.
These stackers can be used in a many fields, e.g., they can be used for forming packages in the field of publishing, food-stuffs packaging, postal services, and the like.
One of these known kinds of stackers is disclosed, e.g., in U.S. Pat. No. 3,937,456 (Gruodis et al.). It comprises a movable article transporter, inclined slides located beneath the transporter, and containers having three sides and an open top, located at the lower end of the slides.
The containers are mounted on respective sensor controlled elevators for adjusting the height of the containers in accordance with the height of the stack detected by the sensors.
When a container is full, it is replaced with an empty one.
The containers have an inclined interior floor surface and are of a very complicated structure. Moreover, when one or more stacks of articles are to be formed within a package, it is necessary to remove manually the finished stacks from the containers and place them in the package, which represents an additional cost. Further, the stacker as a whole is somewhat complicated and expensive.
In U.S. Pat. No. 3,888,363 (Erekson) there is disclosed an indexing stacker for flat objects. It is composed of four compartments and the articles are delivered to each compartment by conveying means. When a stack of a predetermined number of articles is formed in the compartment, the stacker is indexed 90 degrees and an empty compartment faces the output of the conveyor in order to be filled. When all the four compartments are filled with the required number of articles, the finished stacks are removed, either manually or through automated means, and placed in a box.
Thus, this type of stacker involves an additional operation and therefore an additional cost. Moreover, this device is somewhat complicated and expensive, too.
Other stacking devices are based upon modules having a bottom surface which is opened like a hinged trapdoor over the container allowing the carried article to be dropped into the container. However, these devices, besides requiring a complicated mechanism for opening and closing the bottom whereby they are subjected to jamming, require a certain spacing between the container and the trapdoor in order to permit the downwards opening of the latter, and, because of the long trajectory of the falling articles, the resulting stacking is not very tidy.